The Self-Organizing Network (SON) is a technique for automating configuration, optimization and healing in a radio network and mainly aims to improve the quality of the radio network and reduce the cost for operating the radio network. The Third Generation Partnership Project (3GPP) mainly standardizes the SON in the Long Term Evolution (LTE) and the LTE-Advanced (see Non-Patent Literature 1 and 2). The SON operations include, for example, self-configuration operations, self-optimization operations, and self-healing operations.
In the self-optimization operations, configuration parameters of one or more base stations are automatically adjusted in order to improve the quality of the radio network based on various types of information observed by base stations (or mobile stations). The configuration parameters of a base station have an influence on operations of one or both of a base station and a mobile station. The self-optimization operations include, for example, Automatic Neighbour Relations (ANR), Mobility Robustness Optimization (MRO), Coverage and Capacity Optimization (CCO), Mobility Load Balancing (MLB), Cell Range Expansion (CRE), energy saving management, inter-cell interference reduction, and Random Access Channel (RACH) optimization.
The SON architecture includes centralized architecture, distributed architecture, and hybrid architecture. In the centralized architecture, a SON entity arranged in a central node (e.g., operational support systems (OSS)) executes SON operations for a plurality of base stations. In the distributed architecture, a SON entity that executes SON operations is arranged in each base station, and the optimization of the whole radio network is achieved by communications among base stations. In the hybrid architecture, both the centralized architecture and the distributed architecture are used. For example, in the hybrid architecture, some SON operations are executed in the centralized architecture and other SON operations are executed by in the distributed architecture.